Ask an expert: Why has my husband been so bad tempered and stressed since our baby was born?

A US researcher highlights possible biological causes of postnatal depression in new dads, as well as how to deal with the problem.

I've got a two-month-old baby and my husband has become increasingly bad-tempered and stressed since she was born. Is this likely to be some kind of postnatal depression, and what can we do about it?

Dr Darby Saxbe, an assistant professor at the University of Southern California's psychology department, has just led a study into parents' biological responses in he early months of a child's life.

She says: "It's common to feel tired, stressed, and short-tempered in early parenthood. You've got a tiny creature waking you up every few hours, demanding to be held and fed, and your pre-baby life and self are forever changed.

"Who wouldn't be overwhelmed? We often hear about the bliss of welcoming a new baby, but less often about how exhausting, lonely, and frustrating those first few months can be.

"Postnatal depression can affect both mothers and fathers, and may be biologically-based. My research team recently published a study which found men with lower testosterone reported more depressive symptoms during the postpartum period. Testosterone tends to drop in men during the transition to parenthood, which may help explain why depression risk increases during this time.

"If your husband seems particularly hopeless and sad, isn't enjoying activities that usually give him pleasure, and can't be cheered up, he may be depressed. The first line of defence is self-care: sleep, exercise, and socialising are all known to reduce depression risk, so encourage him to prioritise healthy habits.

"If his mood doesn't lift, talk therapy can be very effective for depression, particularly research-supported treatments like cognitive-behavioural therapy."